The present invention relates to an image forming apparatus that performs a thermal fixing operation. More specifically, the present invention relates to an image forming apparatus that performs a plurality of transfer and fixing operations on a same recording medium.
When a conventional image forming apparatus performs a printing operation, for example, toner images in colors of magenta, cyan, yellow, and black are sequentially overlapped to form a color image on a recording medium, and the color image is fixed to the recording medium. Afterward, in order to obtain a text image with gloss image quality, a transparent toner image is overlapped and transferred to the color image in a later stage, and the transparent toner image is fixed (refer to Patent Reference). In the following description, such an operation, in which the transfer operation and the fixing operation are performed twice on a same surface of a same recording medium, may be referred to as a two-pass printing operation.
Patent Reference: Japanese Patent Publication No. 2010-250055
In the conventional image processing system disclosed in Patent Reference, when the transfer operation and the fixing operation are performed twice using the different types of developer, i.e., color toner and transparent toner, there may be a problem due to various fixing properties according to developer.
An object of the present invention is to provide an image forming apparatus capable of solving the problems.
Further objects and advantages of the invention will be apparent from the following description of the invention.